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Cloud Service Providers are speedily becoming the target platform for scientific workflow computations due to the massive possible and flexible pay-as-you-go pricing model. Workflow allocation problem in cloud systems is considered NP-hard. A heterogeneous IaaS cloud could be fully effective if the allocation method provides an efficient mapping between virtual machines (VMs) and workflow applications demanding execution. First, we model multiple workflow allocation problem in the cloud environment. Then, we propose a levelized multiple workflow allocation strategy with task merging (LMWS-TM) to optimize turnaround time for multiple workflow applications in the Infrastructure as a Service (IaaS) cloud environment to achieve better performance. The task merging scheme is incorporated into workflows after partitioning and prior to allocation to reduce inter-task communication share and the total number of depth levels for improving the overall completion time. Moreover, it considers inter-task communication and inter-machine distance for estimating communication cost share among tasks on the schedule generated. Furthermore, the scheme is capable enough to use simple and flexible level attributes to tackle precedence constraints. Afterward, we conducted an experimental study to evaluate LMWS-TM by comparative performance analysis with its peers, namely SLBBS, DLS, and HEFT, on quality of service (QoS) parameters, namely, turnaround time, system utilization, flow time, and response time. The study reveals the superior performance of LMWS-TM among its considered peers in almost all the cases for almost all considered parameters under investigation. Finally, we performed statistical testing to test the significance level using SPSS 20, confirming the hypothesis drawn in the experimental study. |
